Impact experiments into multiple-mesh targets: Concept development of a lightweight collisional bumper

The utility of multiple-mesh targets as potential lightweight shields to protect spacecraft in low-Earth orbit against collisional damage is explored. Earlier studies revealed that single meshes comminute hypervelocity impactors with efficiencies comparable to contiguous targets. Multiple interaction of projectile fragments with any number of meshes should lead to increased comminution, deceleration, and dispersion of the projectile, such that all debris exiting the mesh stack possesses low specific energies (ergs/sq cm) that would readily be tolerated by many flight systems. The study is conceptually exploring the sensitivity of major variables such as impact velocity, the specific areal mass (g/sq cm) of the total mesh stack (SM), and the separation distance (S) between individual meshes. Most experiments employed five or ten meshes with total SM typically less than 0.5 the specific mass of the impactor, and silicate glass impactors rather than metal projectiles. While projectile comminution increases with increasing impact velocity due to progressively higher shock stresses, encounters with multiple-meshes at low velocity (1-2 km/s) already lead to significant disruption of the glass impactors, with the resulting fragments being additionally decelerated and dispersed by subsequent meshes, and, unlike most contiguous single-plate bumpers, leading to respectable performance at low velocity. Total specific bumper mass must be the subject of careful trade-off studies; relatively massive bumpers will generate too much debris being dislodged from the bumper itself, while exceptionally lightweight designs will not cause sufficient comminution, deceleration, or dispersion of the impactor. Separation distance was found to be a crucial design parameter, as it controls the dispersion of the fragment cloud. Substantial mass savings could result if maximum separation distances were employed. The total mass of debris dislodged by multiple-mesh stacks is modestly smaller than that of single, contiguous-membrane shields. The cumulative surface area of all penetration holes in multiple mesh stacks is an order of magnitude smaller than that in analog multiple-foil shields, suggesting good long-term performance of the mesh designs. Due to different experimental conditions, direct and quantitative comparison with other lightweight shields is not possible at present

Adaptive object management for distributed systems

This thesis describes an architecture supporting the management of pluggable software components and evaluates it against the requirement for an enterprise integration platform for the manufacturing and petrochemical industries. In a distributed environment, we need mechanisms to manage objects and their interactions. At the least, we must be able to create objects in different processes on different nodes; we must be able to link them together so that they can pass messages to each other across the network; and we must deliver their messages in a timely and reliable manner. Object based environments which support these services already exist, for example ANSAware(ANSA, 1989), DEC's Objectbroker(ACA,1992), Iona's Orbix(Orbix,1994)Yet such environments provide limited support for composing applications from pluggable components. Pluggability is the ability to install and configure a component into an environment dynamically when the component is used, without specifying static dependencies between components when they are produced. Pluggability is supported to a degree by dynamic binding. Components may be programmed to import references to other components and to explore their interfaces at runtime, without using static type dependencies. Yet thus overloads the component with the responsibility to explore bindings. What is still generally missing is an efficient general-purpose binding model for managing bindings between independently produced components. In addition, existing environments provide no clear strategy for dealing with fine grained objects. The overhead of runtime binding and remote messaging will severely reduce performance where there are a lot of objects with complex patterns of interaction. We need an adaptive approach to managing configurations of pluggable components according to the needs and constraints of the environment. Management is made difficult by embedding bindings in component implementations and by relying on strong typing as the only means of verifying and validating bindings. To solve these problems we have built a set of configuration tools on top of an existing distributed support environment. Specification tools facilitate the construction of independent pluggable components. Visual composition tools facilitate the configuration of components into applications and the verification of composite behaviours. A configuration model is constructed which maintains the environmental state. Adaptive management is made possible by changing the management policy according to this state. Such policy changes affect the location of objects, their bindings, and the choice of messaging system

Low-Cost Sensors and Biological Signals

Many sensors are currently available at prices lower than USD 100 and cover a wide range of biological signals: motion, muscle activity, heart rate, etc. Such low-cost sensors have metrological features allowing them to be used in everyday life and clinical applications, where gold-standard material is both too expensive and time-consuming to be used. The selected papers present current applications of low-cost sensors in domains such as physiotherapy, rehabilitation, and affective technologies. The results cover various aspects of low-cost sensor technology from hardware design to software optimization

Material agency and performative dynamics in the practices of media art

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel UniversityThis dissertation identifies a strategy of artistic inquiry within contemporary media art practice. It applies the concept of material that acts in an agential capacity, generating performative acts. It argues that the emergent potentials of materials and their interconnectedness with the compositional layers of a work can facilitate modes of effecting change in the artistic system. Through the theoretical investigation of the production processes of physical structures and environments, the thesis focuses on the compositional dynamics within which materials actively perform. It examines how Lars Spuybroek’s architectural design method of Material Machines (2004), and both the tactile potential as well as tactical uses of materials as generators to the formtaking process, might describe an open and active artistic strategy for employing the experimental capacities of such materialization processes. Building on philosophical and conceptual arguments that trace concepts of agency (Bruno Latour’s Actant-Network theory) and enactment (Karen Barad’s concept of intra-acting), the thesis introduces the two installation works ANI_MATE (described as a performative pneumatic stage machine) and ON TRACK (described as a mechanic-robotic installation). These apply the introduced artistic strategies. The analyses of these two artworks traces the particular capacities of the materials involved (respectively, their elasticity or viscosity) to negotiate forces of physical movement, which effect the system to transiently or irreversibly transform. ANI_MATE is a machine that is artist-operated and that explores the relationship between liveanimation procedures and the transformability and flexibility of its material environment. In contrast, ON TRACK’s performative machine ecology removes human agency. The machines act autonomously, giving rise to chance in the artistic system and allowing agency to emerge from the dynamic interconnectivity between materials, parts, and processes, eventually producing an entropic scenario of spilling resources. The thesis concludes that, in the context of a post digital paradigm in-development, such artistic practice offers a new strategy for an emergent aesthetics within contemporary physical-digital performance

A Presence-Based Architecture for a Gateway to Integrate Vehicular Ad-Hoc Networks (VANETs), the IP Multimedia Subsystems (IMS) and Wireless Sensor Networks (WSNs)

Résumé Le IP Multimedia Subsystems (IMS) est un sujet de recherche qui attire l’attention de la communauté de recherche. Il a comme but de fournir un accès mobile aux différents services internet. Il s’agit d’une architecture de contrôle au-dessus de la couche IP dont le but est de fournir une qualité de service, services intégrés et un système de tarification équitable à travers des interfaces standards. D’autre part, le réseau Ad-hoc de véhicules (VANETs) fournit un nouveau moyen de communication sans-fil entre les véhicules circulants à grande vitesse ainsi que les équipements installés tout au long des côtés de la route. Cette technologie ouvre la porte pour développer des applications diverses comme la génie de trafic, gestion du trafic, diffusion d’information en cas d’urgence pour éviter des situations critiques, divertissement et bien d’autres choses. VANETs forme une sous-classe des réseaux Ad-hoc mobile dont la performance est fortement liée au protocole de routage utilisé dans le réseau. L’intégration des deux technologies, IMS et VANET, permettra de mettre en œuvre de nouveaux services multimédias. Ce mémoire de maîtrise propose une architecture d’une passerelle incorporant ces deux technologies ensemble. Étant donné que les deux architectures utilisent des formats de communication différents, on a conçu un middleware afin d’adapter le format en fonction de la destination et de choisir la meilleur stratégie de livraison d’information entre eux. La passerelle, qui est le cœur de notre architecture, est une couche au-dessus du IMS et le VANET. ----------ABSTRACT On one hand, IP Multimedia Subsystems (IMS) are a research area that has been gaining attention from the research community. It aims to provide cellular access to all Internet services. It is a control architecture on the top of the IP layer whose goal is dependent on the provision of the Quality of Service (QoS), integrated services and fair charging scheme throughout standard interfaces. On the other hand, Vehicular Ad-hoc Networks (VANETs) are a new communication paradigm that enables the wireless communication between vehicles moving with high speeds, as well as the vehicles and the road side equipments found along the roads. This opened the door to develop several new applications like, traffic engineering, traffic management, dissemination of emergency information to avoid critical situations, comfort and entertainment and other user applications. Moreover, VANETs are a sub-class of mobile ad-hoc networks; the performance of the communication depends on how better the routing takes place in the network. Routing of data depends on the routing protocols being used in the network. Combining the capabilities of IMS world with the VANET world opens the door to deploy a wide range of novel multimedia services. This dissertation proposes a presence-based architecture for the integration of IMS with VANETs. The presence of the middleware is used to make an instantaneous awareness of the VANETs changes as well as of the IMS format and to select the best delivery strategy between the two architectures. The gateway which is the heart of our architecture is an overlay built on the top of the IMS as well as the VANETs

Bibliografische Daten, Normdaten und Metadaten im Semantic Web : Konzepte der Bibliografischen Kontrolle im Wandel

Diese Veröffentlichung geht zurück auf eine Magisterarbeit (2010) im Direktstudiengang Bibliothekswissenschaft an der Humboldt-Universität zu Berlin.Die Informationsräume Bibliothek und World Wide Web (WWW) stehen vor der gleichen Herausforderung: Eine korrekte, umfassende und nutzergerechte Erschliessung ihrer Dokumente zu leisten. Eine Lösung aus beiden Perspektiven wäre eine einfache und universelle Ressourcenbeschreibung, die implizit generiert wird. Hieraus ergibt sich eine zentrale Frage für die Bibliothekswissenschaft: Inwieweit und auf welche Weise können solche Techniken auch für die Bibliografische Kontrolle nutzbar gemacht werden? Im ersten Teil der Arbeit werden die klassischen Konzepte der Bibliografischen Kontrolle analysiert. Als aktuelle Umformungen dieser Komponenten wird auf die Konzeptmodelle des "Bibliografischen Universums" FRBR, FRAD und FRSAD eingegangen. Das Begriffskontinuum Metadaten und Ressourcenbeschreibung wird erläutert und als Bibliografisches System redefiniert, bevor die gegenwärtigen Metadatensystemen abschliessend kritisch betrachtet werden. Im zweiten Teil werden Prinzipien und Technologien beschrieben, die unter dem Begriff Semantic Web zusammengefasst werden und die Struktur des WWW durch maschinenverarbeitbare Informationen erweitern sollen. Ein Überblick über aktuelle Anwendungen in Form von Linked-Data-Projekten schliesst den Teil ab. Im letzten Abschnitt wird erläutert, wie Bibliografische Metadatensysteme durch die vorgestellten Semantic-Web-Techniken reformuliert und integriert werden können. Dies wird danach anhand des DCAM und konkreter Darstellungen von bibliografischen Metadatenschemata, Normdaten und Kontrollierten Vokabularen mittels RDF(S)/SKOS veranschaulicht. Schliesslich wird das neue Katalogisierungsregelwerk Resource Description and Access (RDA) vor diesem Hintergrund betrachtet. Die Arbeit endet mit der Schlussfolgerung, dass Semantic-Web-Techniken dazu geeignet erscheinen, die strukturelle und inhaltliche Komplexität von bibliografischen Metadaten einheitlich darzustellen sowie diese hochgradig anpassungsfähig und universell verarbeitbar zu gestalten. Im Gegenzug können qualitativ hochwertige bibliothekarische Daten als wichtige Referenzpunkte in der sich rasch entwickelnden Linked Data Cloud fungieren - und ihrerseits in ungeahntem Ausmass verknüpft und somit angereichert werden

Derivation of forest inventory parameters from high-resolution satellite imagery for the Thunkel area, Northern Mongolia. A comparative study on various satellite sensors and data analysis techniques.

With the demise of the Soviet Union and the transition to a market economy starting in the 1990s, Mongolia has been experiencing dramatic changes resulting in social and economic disparities and an increasing strain on its natural resources. The situation is exacerbated by a changing climate, the erosion of forestry related administrative structures, and a lack of law enforcement activities. Mongolia’s forests have been afflicted with a dramatic increase in degradation due to human and natural impacts such as overexploitation and wildfire occurrences. In addition, forest management practices are far from being sustainable. In order to provide useful information on how to viably and effectively utilise the forest resources in the future, the gathering and analysis of forest related data is pivotal. Although a National Forest Inventory was conducted in 2016, very little reliable and scientifically substantiated information exists related to a regional or even local level. This lack of detailed information warranted a study performed in the Thunkel taiga area in 2017 in cooperation with the GIZ. In this context, we hypothesise that (i) tree species and composition can be identified utilising the aerial imagery, (ii) tree height can be extracted from the resulting canopy height model with accuracies commensurate with field survey measurements, and (iii) high-resolution satellite imagery is suitable for the extraction of tree species, the number of trees, and the upscaling of timber volume and basal area based on the spectral properties. The outcomes of this study illustrate quite clearly the potential of employing UAV imagery for tree height extraction (R2 of 0.9) as well as for species and crown diameter determination. However, in a few instances, the visual interpretation of the aerial photographs were determined to be superior to the computer-aided automatic extraction of forest attributes. In addition, imagery from various satellite sensors (e.g. Sentinel-2, RapidEye, WorldView-2) proved to be excellently suited for the delineation of burned areas and the assessment of tree vigour. Furthermore, recently developed sophisticated classifying approaches such as Support Vector Machines and Random Forest appear to be tailored for tree species discrimination (Overall Accuracy of 89%). Object-based classification approaches convey the impression to be highly suitable for very high-resolution imagery, however, at medium scale, pixel-based classifiers outperformed the former. It is also suggested that high radiometric resolution bears the potential to easily compensate for the lack of spatial detectability in the imagery. Quite surprising was the occurrence of dark taiga species in the riparian areas being beyond their natural habitat range. The presented results matrix and the interpretation key have been devised as a decision tool and/or a vademecum for practitioners. In consideration of future projects and to facilitate the improvement of the forest inventory database, the establishment of permanent sampling plots in the Mongolian taigas is strongly advised.2021-06-0

Erweiterte virtuelle Umgebungen zur interaktiven, immersiven Verwendung von Funktionsmodellen

Dem Erkennen und Verstehen von komplexen Produktabhängigkeiten u. a. durch Visualisierung, auch über die klassischen Domänengrenzen hinweg, kommt eine zentrale Bedeutung, insbesondere während den frühen Konstruktionsphasen, zu. Im Rahmen dieser Arbeit wurde ein Prototyp entwickelt, mit dessen Hilfe Funktionsmodelle in virtuelle Umgebungen übertragen und interaktiv genutzt werden können. Dies fördert das interdisziplinäre Gesamtverständnis und unterstützt eine frühzeitige Qualitätskontrolle

Ballistic Missile Defence for Australia

Ballistic missiles are central to rogue states' strategies to deter and coerce Western democracies in the post-Cold War world. The proliferation of missiles of longer and longer range continues throughout the world, and Australia may come within the range of missiles from North Korea and Iran in the coming decade. Regarding rogue states' ballistic missiles, the United States, Japan and some members of NATO are moving from a posture of deterrence through nuclear punishment to a posture of deterrence through denial. Australia, as a beneficiary of the extended US nuclear deterrent, will have to decide whether to participate in 'extended' US missile defence. Various elements of a ballistic missile defence system, effective against the whole threat spectrum, are under development. The technical limitations of these systems and the importance of the BMD systems architecture (shootlook- shoot capability, layered defence) make it important to define what role Australian BMD systems should play in the overall BMD architecture and what exactly Australia wants to achieve with its BMD systems: defending the Australian homeland against direct or seaborne attack, defence of forward deployed troops or strengthening the US alliance. Each of these missions leads to a different prioritisation of available BMD systems, and no system (for example the SEA 4000 destroyer) will be able to achieve all missions. After looking at the technical aspects of several possible Australian BMD architectures, the paper concludes with recommendations for Australia's BMD policy